General purpose, multiple precision parallel operation, programmable media processor

ABSTRACT

A general purpose, programmable media processor for processing and transmitting a media data stream of audio, video, radio, graphics, encryption, authentication, and networking information in real-time. The media processor incorporates an execution unit that maintains substantially peak data throughout of media data streams. The execution unit includes a dynamically partionable multi-precision arithmetic unit, programmable switch and programmable extended mathematical element. A high bandwidth external interface supplies media data streams at substantially peak rates to a general purpose register file and the multi-precision execution unit. A memory management unit, and instruction and data cache/buffers are also provided. High bandwidth memory controllers are linked in series to provide a memory channel to the general purpose, programmable media processor. The general purpose, programmable media processor is disposed in a network fabric consisting of fiber optic cable, coaxial cable and twisted pair wires to transmit, process and receive single or unified media data streams. Parallel general purpose media processors are disposed throughout the network in a distributed virtual manner to allow for multi-processor operations and sharing of resources through the network. A method for receiving, processing and transmitting media data streams over the communications fabric is also provided.

This is a divisional of application Ser. No. 08/516,036, filed Aug. 16,1995, now U.S. Pat. No. 5,742,840.

A Microfiche Appendix consisting of 4 sheets (387 total frames) ofmicrofiche is included in this application. The Microfiche Appendixcontains material which is subject to copyright protection. Thecopyright owner has no objection to the facsimile reproduction by anyone of the Microfiche Appendix, as it appears in the Patent andTrademark Office patent files or records, but otherwise reserves allcopyright rights whatsoever.

FIELD OF THE INVENTION

This invention relates to the field of communications processing, andmore particularly, to a method and apparatus for real-time processing ofmulti-media digital communications.

BACKGROUND OF THE INVENTION

Optical fiber and discs have made the transmission and storage ofdigital information both cheaper and easier than older analogtechnologies. An improved system for digital processing of media datastreams is necessary in order to realize the full potential of theseadvanced media.

For the past century, telephone service delivered over copper twistedpair has been the lingua franca of communications. Over the nextcentury, broadband services delivered over optical fiber and coax willmore completely fulfill the human need for sensory information bysupplying voice, video, and data at rates of about 1,000 times greaterthan narrow band telephony. Current general-purpose microprocessors anddigital signal processors ("DSPs") can handle digital voice, data, andimages at narrow band rates, but they are way too slow for processingmedia data at broadband rates.

This shortfall in digital processing of broadband media is currentlybeing addressed through the design of many different kinds ofapplication-specific integrated circuits ("ASICs"). For example, aprototypical broadband device such as a cable modem modulates anddemodulates digital data at rates up to 45 Mbits/sec within a single 6MHZ cable channel (as compared to rates of 28.8 Kbits/sec within a 6 KHzchannel for telephone modems) and transcodes it onto a 10/100 base Tconnection to a personal computer ("PC") or workstation. Current cablemodems thus receive data from a coaxial cable connection through a chainof specialized ASIC devices in order to accomplish Quadrature AmplitudeModification ("QAM") demodulation, Reed-Solomon error correction, packetfiltering, Data Encryption Standard ("DES") decryption, and Ethernetprotocol handling. The cable modems also transmit data to the coaxialcable link through a second chain of devices to achieve DES encryption,Reed-Solomon block encoding, and Quaternary Phase Shift Keying ("QPSK")modulation. In these environments, a general-purpose processor isusually required as well in order to perform initialization, statisticscollection, diagnostics, and network management functions.

The ASIC approach to media processing has three fundamental flaws: cost,complexity, and rigidity. The combined silicon area of all thespecialized ASIC devices required in the cable modem, for example,results in a component cost incompatible with the per subscriber pricetarget for a cable service. The cable plant itself is a very hostileservice environment, with noise ingress, reflections, nonlinearamplifiers, and other channel impairments, especially when viewed in theupstream direction. Telephony modems have developed an elaboratehierarchy of algorithms implemented in DSP software, with automaticreduction of data rates from 28.8 Kbits/sec to 19.6 Kbits/sec, 14.4Kbits/sec, or much lower rates as needed to accommodate noise, echoes,and other impairments in the copper plant. To implement similaralgorithms on an ASIC-based broadband modem is far more complex toachieve in software.

These problems of cost, complexity, and rigidity are compounded furtherin more complete broadband devices such as digital set-top boxes,multimedia PCs, or video conferencing equipment, all of which go beyondthe basic radio frequency ("RF") modem functions to include a broadrange of audio and video compression and decoding algorithms, along withremote control and graphical user interfaces. Software for these devicesmust control what amounts to a heterogeneous multi-processor, where eachspecialized processor has a different, and usually eccentric orprimitive, programming environment. Even if these programmingenvironments are mastered, the degree of programmability is limited. Forexample, Motion Picture Expert Group-I ("MPEG-I") chips manufactured byAT&T Corporation will not implement advances such as fractal- andwavelet-based compression algorithms, but these chips are not readilysoftware upgradeable to the MPEG-II standard. A broadband networkoperator who leases an MPEG ASIC-based product is therefore at risk ofhaving to continuously upgrade his system by purchasing significantamounts of new hardware just to track the evolution of MPEG standards.

The high cost of ASIC-based media processing results from inefficienciesin both memory and logic. A typical ASIC consists of a multiplicity ofspecialized logic blocks, each with a small memory dedicated to holdingthe data which comprises the working set for that block. The siliconarea of these multiple small memories is further increased by theoverhead of multiple decoders, sense amplifiers, write drivers, etc.required for each logic block. The logic blocks are also constrained tooperate at frequencies determined by the internal symbol rates ofbroadband algorithms in order to avoid additional buffer memories. Thesefrequencies typically differ from the optimum speed-area operating pointof a given semiconductor technology. Interconnect and synchronization ofthe many logic and memory blocks are also major sources of overhead inthe ASIC approach.

The disadvantages of the prior ASIC approach can be over come by asingle unified media processor. The cost advantages of such a unifiedprocessor can be achieved by gathering all the many ASIC functions of abroadband media product into a single integrated circuit. Cost reductionis further increased by reducing the total memory area of such a circuitby replacing the multiplicity of small ASIC memories with a singlememory hierarchy large enough to accommodate the sum total of all theworking sets, and wide enough to supply the aggregate bandwidth needs ofall the logic blocks. Additionally, the logic block interconnectcircuitry to this memory hierarchy may be streamlined by providing agenerally programmable switching fabric. Many of the logic blocksthemselves can also replaced with a single multi-precision arithmeticunit, which can be internally partitioned under software control toperform addition, multiplication, division, and other integer andfloating point arithmetic operations on symbol streams of varyingwidths, while sustaining the full data throughput of the memoryhierarchy. The residue of logic blocks that perform operations that areneither arithmetic or permutation group oriented can be replaced with anextended math unit that supports additional arithmetic operations suchas finite field, ring, and table lookup, while also sustaining the fulldata throughput of the memory hierarchy.

The above multi-precision arithmetic, permutation switch, and extendedmath operations can then be organized as machine instructions thattransfer their operands to and from a single wide multi-ported registerfile. These instructions can be further supplemented with load/storeinstructions that transfer register data to and from a data buffer/cachestatic random access memory ("SRAM") and main memory dynamic randomaccess memories ("DRAMs"), and with branch instructions that control theflow of instructions executed from an instruction buffer/cache SRAM.Extensions to the load/store instructions can be made forsynchronization, and to branch instructions for protected gateways, sothat multiple threads of execution for audio, video, radio, encryption,networking, etc. can efficiently and securely share memory and logicresources of a unified machine operating near the optimum speed-areapoint of the target semiconductor process. The data path for such aunified media processor can interface to a high speed input/output("I/O") subsystem that moves media streams across ultra-high bandwidthinterfaces to external storage and I/O.

Such a device would incorporate all of the processing capabilities ofthe specialized multi-ASIC combination into a single, unified processingdevice. The unified processor would be agile and capable ofreprogramming through the transmission of new programs over thecommunication medium. This programmable, general purpose device is thusless costly than the specialized processor combination, easier tooperate and reprogram and can be installed or applied in many differingdevices and situations. The device may also be scalable tocommunications applications that support vast numbers of users throughmassively parallel distributed computing.

It is therefore an object of this invention to process media datastreams by executing operations at very high bandwidth rates.

It is also an object of this invention to unify the audio, video, radio,graphics, encryption, authentication, and networking protocols into asingle instruction stream.

It is also an object of this invention to achieve high bandwidth ratesin a unified processor that is easy to program and more flexible than aheterogeneous combination of special purpose processors.

It is a further object of the invention to support high levelmathematical processing in a unified media processor, including finitegroup, finite field, finite ring and table look-up operations, all athigh bandwidth rates.

It is yet a further object of the invention to provide a unified mediaprocessor that can be replicated into a multi-processor system tosupport a vast array of users.

It is yet another object of this invention to allow for massivelyparallel systems within the switching fabric to support very largenumbers of subscribers and services.

It is also an object of the invention to provide a general purposeprogrammable processor that could be employed at all points in anetwork.

It is a further object of this invention to sustain very high bandwidthrates to arbitrarily large memory and input/output systems.

SUMMARY OF THE INVENTION

In view of the above, there is provided a system for media processingthat maintains substantially peak data throughput in the execution andtransmission of multiple media data streams. The system includes in oneaspect a general purpose, programmable media processor, and in anotheraspect includes a method for receiving, processing and transmittingmedia data streams. The general purpose, programmable media processor ofthe invention further includes an execution unit, high bandwidthexternal interface, and can be employed in a parallel multi-processorsystem.

According to the apparatus of the invention, an execution unit isprovided that maintains substantially peak data throughput in theunified execution of multiple media data streams. The execution unitincludes a data path, and a multi-precision arithmetic unit coupled tothe data path and capable of dynamic partitioning based on the elementalwidth of data received from the data path. The execution unit alsoincludes a switch coupled to the data path that is programmable tomanipulate data received from the data path and provide data streams tothe data path. An extended mathematical element is also provided, whichis coupled to the data path and programmable to implement additionalmathematical operations at substantially peak data throughput. In apreferred embodiment of the execution unit, at least one register fileis coupled to the data path.

According to another aspect of the invention, a general purposeprogrammable media processor is provided having an instruction path anda data path to digitally process a plurality of media data streams. Themedia processor includes a high bandwidth external interface operable toreceive a plurality of data of various sizes from an external source andcommunicate the received data over the data path at a rate thatmaintains substantially peak operation of the media processor. At leastone register file is included, which is configurable to receive andstore data from the data path and to communicate the stored data to thedata path. A multi-precision execution unit is coupled to the data pathand is dynamically configurable to partition data received from the datapath to account for the elemental symbol size of the plurality of mediastreams, and is programmable to operate on the data to generate aunified symbol output to the data path.

According to the preferred embodiment of the media processor, means areincluded for moving data between registers and memory by performing loadand store operations, and for coordinating the sharing of data among aplurality of tasks by performing synchronization operations based uponinstructions and data received by the execution unit. Means are alsoprovided for securely controlling the sequence of execution byperforming branch and gateway operations based upon instructions anddata received by the execution unit. A memory management unit operableto retrieve data and instructions for timely and secure communicationover the data path and instruction path respectively is also preferablyincluded in the media processor. The preferred embodiment also includesa combined instruction cache and buffer that is dynamically allocatedbetween cache space and buffer space to ensure real-time execution ofmultiple media instruction streams, and a combined data cache and bufferthat is dynamically allocated between cache space and buffer space toensure real-time response for multiple media data streams.

In another aspect of the invention, a high bandwidth processor interfacefor receiving and transmitting a media stream is provided having a datapath operable to transmit media information at sustained peak rates. Thehigh bandwidth processor interface includes a plurality of memorycontrollers coupled in series to communicate stored media information toand from the data path, and a plurality of memory elements coupled inparallel to each of the plurality of memory controllers for storing andretrieving the media information. In the preferred embodiment of thehigh bandwidth processor interface, the plurality of memory controllerseach comprise a paired link disposed between each memory controller,where the paired links each transmit and receive plural bits of data andhave differential data inputs and outputs and a differential clocksignal.

Yet another aspect of the invention includes a system for unified mediaprocessing having a plurality of general purpose media processors, whereeach media processor is operable at substantially peak data rates andhas a dynamically partitioned execution unit and a high bandwidthinterface for communicating to memory and input/output elements tosupply data to the media processor at substantially peak rates. Abi-directional communication fabric is provided, to which the pluralityof media processors are coupled, to transmit and receive at least onemedia stream comprising presentation, transmission, and storage mediainformation. The bi-directional communication fabric preferablycomprises a fiber optic network, and a subset of the plurality of mediaprocessors comprise network servers.

According to yet another aspect of the invention, a parallel multi-mediaprocessor system is provided having a data path and a high bandwidthexternal interface coupled to the data path and operable to receive aplurality of data of various sizes from an external source andcommunicate the received data at a rate that maintains substantiallypeak operation of the parallel multi-processor system. A plurality ofregister files, each having at least one register coupled to the datapath and operable to store data, are also included. At least onemulti-precision execution unit is coupled to the data path and isdynamically configurable to partition data received from the data pathto account for the elemental symbol size of the plurality of mediastreams, and is programmable to operate in parallel on data stored inthe plurality of register files to generate a unified symbol output foreach register file.

According to the method of the invention, unified streams of media dataare processed by receiving a stream of unified media data includingpresentation, transmission and storage information. The unified streamof media data is dynamically partitioned into component fields of atleast one bit based on the elemental symbol size of data received. Theunified stream of media data is then processed at substantially peakoperation.

In one aspect of the invention, the unified stream of media data isprocessed by storing the stream of unified media data in a generalregister file. Multi-precision arithmetic operations can then beperformed on the stored stream of unified media data based on programmedinstructions, where the multi-precision arithmetic operations includeBoolean, integer and floating point mathematical operations. Thecomponent fields of unified media data can then be manipulated based onprogrammed instructions that implement copying, shifting and re-sizingoperations. Multi-precision mathematical operations can also beperformed on the stored stream of unified media data based on programmedinstructions, where the mathematical operations including finite group,finite field, finite ring and table look-up operations. Instruction anddata pre-fetching are included to fill instruction and data pipelines,and memory management operations can be performed to retrieveinstructions and data from external memory. The instructions and dataare preferably stored in instruction and data cache/buffers, in whichbuffer storage in the instruction and data cache/buffers is dynamicallyallocated to ensure real-time execution.

Other aspects of the invention include a method for achieving highbandwidth communications between a general purpose media processor andexternal devices by providing a high bandwidth interface disposedbetween the media processor and the external devices, in which the highbandwidth interface comprises at least one uni-directional channel pairhaving an input port and an output port. A plurality of media datastreams, comprising component fields of various sizes, are transmittedand received between the media processor and the external devices at arate that sustains substantially peak data throughput at the mediaprocessor. A method for processing streams of media data is alsoincluded that provides a bi-directional communications fabric fortransmitting and receiving at least one stream of media data, where theat least one stream of media data comprises presentation, transmissionand storage information. At least one programmable media processor isprovided within the communications network for receiving, processing andtransmitting the at least one stream of unified media data over thebi-directional communications fabric.

The general purpose, programmable media processor of the inventioncombines in a single device all of the necessary hardware included inthe specialized processor combinations to process and communicatedigital media data streams in real-time. The general purpose,programmable media processor is therefore cheaper and more flexible thanthe prior approach to media processing. The general purpose,programmable media processor is thus more susceptible to incorporationwithin a massively parallel processing network of general purpose mediaprocessors that enhance the ability to provide real-time multi-mediacommunications to the masses.

These features are accomplished by deploying server media processors andclient media processors throughout the network. Such a network providesa seamless, global media super-computer which allows programmers andnetwork owners to virtualize resources. Rather than restrictivelyaccessing only the memory space and processing time of a local resource,the system allows access to resources throughout the network. In smallaccess points such as wireless devices, where very little memory andprocessing logic is available due to limited battery life, the system isable to draw upon the resources of a homogeneous multi-computer system.

The invention also allows network owners the facility to track standardsand to deploy new services by broadcasting software across the networkrather than by instituting costly hardware upgrades across the wholenetwork. Broadcasting software across the network can be performed atthe end of an advertisement or other program that is broadcastednationally. Thus, services can be advertised and then transmitted to newsubscribers at the end of the advertisement.

These and other features and advantages of the invention will beapparent upon consideration of the following detailed description of thepresently preferred embodiments of the invention, taken in conjunctionwith the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a broad band media computer employing thegeneral purpose, programmable media processor of the invention;

FIG. 2 is a block diagram of a global media processor employing multiplegeneral purpose media processors according to the invention;

FIG. 3 is an illustration of the digital bandwidth spectrum fortelecommunications, media and computing communications;

FIG. 4 is the digital bandwidth spectrum shown in FIG. 3 taking intoaccount the bandwidth overhead associated with compressed videotechniques;

FIG. 5 is a block diagram of the current specialized processor solutionfor mass media communication, where FIG. 5 shows the current distributedsystem, and shows a possible integrated approach;

FIG. 6 is a block diagram of two presently preferred general purposemedia processors, where FIG. 6 shows a distributed system and shows anintegrated media processor;

FIG. 7 is a block diagram of the presently preferred structure of ageneral purpose, programmable media processor according to theinvention;

FIG. 8 is a drawing consisting of visual illustrations of the variousgroup operations provided on the media processor, where FIG. 8(a)illustrates the group expand operation, FIG. 8(b) illustrates the groupcompress or extract operation, FIG. 8(c) illustrates the group deal andshuffle operations, FIG. 8(d) illustrates the group swizzle operationand FIG. 8(e) illustrates the various group permute operations;

FIG. 9 shows the preferred instruction and data sizes for the generalpurpose, programmable media processor, where FIG. 9(a) is anillustration of the various instruction formats available on the generalpurpose, programmable media processor, FIG. 9(b) illustrates the variousfloating-point data sizes available on the general purpose mediaprocessor, and FIG. 9(c) illustrates the various fixed-point data sizesavailable on the general purpose media processor;

FIG. 10 is an illustration of a presently preferred memory managementunit included in the general purpose processor shown in FIG. 7, whereFIG. 10(a) is a translation block diagram and FIG. 10(b) illustrates thefunctional blocks of the transaction lookaside buffer;

FIG. 11 is an illustration of a super-string pipeline technique;

FIG. 12 is an illustration of the presently preferred super-springpipeline technique;

FIG. 13 is a block diagram of a single memory channel for communicationto the general purpose media processor shown in FIG. 7;

FIG. 14 is an illustration of the presently preferred connection ofstandard memory devices to the preferred memory interface;

FIG. 15 is a block diagram of the input/output controller for use withthe memory channel shown in FIG. 13;

FIG. 16 is a block diagram showing multiple memory channels connected tothe general purpose media processor shown in FIG. 7, where FIG. 16(a)shows a two-channel implementation and FIG. 16(b) illustrates atwelve-channel embodiment;

FIG. 17 illustrates the presently preferred packet communicationsprotocol for use over the memory channel shown in FIG. 13;

FIG. 18 shows a multi-processor configuration employing the generalpurpose media processor shown in FIG. 7, where FIG. 18(a) shows a linearprocessor configuration, FIG. 18(b) shows a processor ringconfiguration, and FIG. 18(c) shows a two-dimensional processorconfiguration; and

FIG. 19 shows a presently preferred multi-chip implementation of thegeneral purpose, programmable media processor of the invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Referring to the drawings, where like-reference numerals refer to likeelements throughout, a broad band microcomputer 10 is provided inFIG. 1. The broad band microcomputer 10 consists essentially of ageneral purpose media processor 12. As will be described in more detailbelow, the general purpose media processor 12 receives, processes andtransmits media data streams in a bi-directional manner from upstreamnetwork components to downstream devices. In general, media data streamsreceived from upstream network components can comprise any combinationof audio, video, radio, graphics, encryption, authentication, andnetworking information. As those skilled in the art will appreciate,however, the general purpose media processor 12 is in no way limited toreceiving, processing and transmitting only these types of mediainformation. The general purpose media processor 12 of the invention iscapable of processing any form of digital media information withoutdeparting from the spirit and essential scope of the invention.

System Configuration

In the preferred embodiment of the invention shown in FIG. 1, media datastreams are communicated to the media processor 12 from several sources.Ideally, unified media data streams are received and transmitted by thegeneral purpose media processor 12 over a fiber optic cable network 14.As will be described in more detail below, although a fiber optic cablenetwork is preferred, the presently existing communications network inthe United States consists of a combination of fiber optic cable,coaxial cable and other transmission media. Consequently, the generalpurpose media processor 12 can also receive and transmit media datastreams over coaxial cable 14 and traditional twisted pair wireconnections 16. The specific communications protocol employed over thetwisted pair 16, whether POTS, ISDN or ADSL, is not essential; allprotocols are supported by the broad band microcomputer 10. The detailsof these protocols are generally known to those skilled in the art andno further discussion is therefore needed or provided herein.

Another form of upstream network communication is through a satellitelink 18. The satellite link 18 is typically connected to a satellitereceiver 20. The satellite receiver 20 comprises an antenna, usually inthe form of a satellite dish, and amplification circuitry. The detailsof such satellite communications are also generally known in the art,and further detail is therefore not provided or included herein.

As described above, the general purpose media processor 12 communicatesin a bi-directional manner to receive, process and transmit media datastreams to and from downstream devices. As shown in FIG. 1, downstreamcommunication preferably takes place in at least two forms. First, mediadata streams can be communicated over a bi-directional local network 22.Various types of local networks 22 are generally known in the art andmany different forms exist. The general purpose media processor 12 iscapable of communicating over any of these local networks 22 and theparticular type of network selected is implementation specific.

The local network 22 is preferably employed to communicate between theunified processor 12, and audio/visual devices 24 or other digitaldevices 26. Presently preferred examples of audio/visual devices 24include digital cable television, video-on-demand devices, electronicyellow pages services, integrated message systems, video telephones,video games and electronic program guides. As those skilled in the artwill appreciate, other forms of audio/video devices are contemplatedwithin the spirit and scope of the invention. Presently preferredembodiments of other digital devices 26 for communication with thegeneral purpose media processor 12 include personal computers,television sets, work stations, digital video camera recorders, andcompact disc read-only memories. As those skilled in the art will alsoappreciate, further digital devices 26 are contemplated forcommunication to the general purpose media processor 12 withoutdeparting from the spirit and scope of the invention.

Second, the general purpose media processor preferably also communicateswith downstream devices over a wireless network 28. In the presentlypreferred embodiment of the invention, wireless devices forcommunication over the wireless network 28 can comprise either remotecommunication devices 30 or remote computing devices 32. Presentlypreferred embodiments of the remote communications devices 30 includecordless telephones and personal communicators. Presently preferredembodiments of the remote computing devices 32 include remote controlsand telecommunicating devices. As those skilled in the art willappreciate, other forms of remote communication devices 30 and remotecomputing devices 32 are capable of communication with the generalpurpose media processor 12 without departing from the spirit and scopeof the invention. An agile digital radio (not shown) that incorporates ageneral purpose media processor 12 may be used to communicate with thesewireless devices.

Network Configuration

Referring now to FIG. 2, the general purpose media processor 12 ispreferably disposed throughout a digital communications network 38. Inorder to enable communication among large and small businesses,residential customers and mobile users, the network 38 can consist of acombination of many individual sub-networks comprised of three mainforms of interconnection. The trunk and main branches of the network 38preferably employ fiber optic cable 40 as the preferred means ofinterconnection. Fiber optic cable 40 is used to connect between generalpurpose media processors 12 disposed as network servers 46 or largebusiness installations 48 that are capable of coupling directly to thefiber optic link 40. For communications to small business andresidential customers that may be incapable of directly coupling to thefiber optic cable 40, a general purpose media processor 12 can be usedas an interface to other forms of network interconnection.

As shown in FIG. 2, alternate forms of interconnection consist ofcoaxial cable lines 42 and twisted pair wiring 44. Coaxial cable linesare currently in place throughout the U.S. and is typically employed toprovide cable television services to residential homes. According to thepreferred embodiment of the invention, general purpose media processors12 can be installed at these residential locations 52. In contrast tothe specialized processor approach, the general purpose media processor12 provides enough bandwidth to allow for bi-directional communicationsto and from these residential locations 52.

Network servers 46 controlled by general purpose media processors 12 arealso employed throughout the network 38. For example, the networkservers 46 can be used to interface between the fiber optic network 40and twisted pair wiring 44. Twisted pair wiring 44 is still employed forsmall businesses 50 and residential locations 52 that do not or cannotcurrently subscribe to coaxial cable or fiber optic network services.General purpose media processors 12 are also disposed at these smallbusiness locations 50 and non-cable residential locations 52. Generalpurpose media processors 12 are also installed in wireless or mobilelocations 52, which are coupled to the network 38 through agile digitalradios (not shown). As shown in FIG. 2, network databases or otherperipherals 56 can also coupled to general purpose media processors 12in the network 38.

The general purpose media processor 12 is operable at significantly highbandwidths in order to receive, process and transmit unified media datastreams. Referring to FIG. 3, the respective frequencies for varioustypes of media data streams are set forth against a bandwidth spectrum60. The bandwidth spectrum 60 includes three component spectrums, allalong the same range of frequencies, which represent the variousfrequency rates of digital media communications. Current computingbandwidth capabilities are also displayed. The telecommunicationsspectrum 62 shows the various frequency bands used fortelecommunications transmission. For example, teletype terminals andmodems operate in a range between approximately 64 bits/second to 16kilobits/second. The ISDN telecommunication protocol operates at 64kilobits/second. At the upper end of the telecommunications spectrum 62,T1 and T3 trunks operate at one megabit per second and 32 megabits persecond, respectively. The SONET frequency range extends fromapproximately 128 megabits per second up to approximately 32 gigabitsper second. Accordingly, in order to carry such broad bandcommunications, the general purpose media processor 12 is capable oftransferring information at rates into the gigabits per second range orhigher.

A spectrum of typical media data streams is presented in the mediaspectrum 64 shown in FIG. 3. Voice and music transmissions are centeredat frequencies of approximately 64 kilobits per second and one megabitper second, respectively. At the upper end of the media spectrum 64,video transmission takes place in a range from 128 megabits per secondfor high density television up to over 256 gigabits per second for movieapplications. When using common video compression techniques, however,the video transmission spectrum can be shifted down to between 32kilobits per second to 128 megabits per second as a result of the datacompression. As described below, the processing required to achieve thedata compression results in an increase in bandwidth requirements.

Current computing bandwidths are shown in the computing spectrum 66 ofFIG. 3. Serial communications presently take place in a range betweentwo kilobits per second up to 512 kilobits per second. The Ethernetnetwork protocol operates at approximately 8 megabits per second.Current dynamic random access memory and other digital input/outputperipherals operate between 32 megabits per second and 512 megabits persecond. Presently available microprocessors are capable of operation inthe low gigabits per second range. For example, the '386 Pentiummicroprocessor manufactured by Intel Corporation of Santa Clara, Calif.operates in the lower half of that range, and the Alpha microprocessormanufactured by Digital Equipment Corporation approaches the 16 gigabitsper second range.

When video compression is employed, as expressed above, the associatedprocessing overhead reduces the effective bandwidth of the particularprocessor. As a result, in order to handle compressed video, theseprocessors must operate in the terahertz frequency range. The bandwidthspectrum 60 shown in FIG. 4 represents the effect of handling media datastreams including compressed video. The computing spectrum 66 is skeweddown to properly align the computing bandwidth requirements with thetelecommunications spectrum 62 and the media spectrum 64. Accordingly,current processor technology is not sufficient to handle thetransmission and processing associated with complex streams ofmulti-media data.

The current specialized processor approach to media processing isillustrated in the block diagram shown in FIG. 5. As shown in FIG. 5,special purpose processors are coupled to a back plane 70, which iscapable of transmitting instructions and data at the upper kilobits tolower gigabits per second range. In a typical configuration, an audioprocessor 76, video processor 78, graphics processor 80 and networkprocessor 82 are all coupled to the back plane 70. Each of the audio,video, graphics and network processors 76-82 typically employ their ownprivate or dedicated memories 84, which are only accessible to thespecific processor and not accessible over the back plane 70. Asdescribed above, however, unless video data streams are constantly beingprocessed, for example, the video processor 78 will sit idle for periodsof time. The computing power of the dedicated video processor 78 is thusonly available to handle video data streams and is not available tohandle other media data streams that are directed to other dedicatedprocessors. This, of course, is an inefficient use of the videoprocessor 78 particularly in view of the overall processing capabilityof this multi-processor system.

The general purpose media processor 12, in contrast, handles a datastream of audio, video, graphics and network information all at the sametime with the same processor. In order to handle the ever changingcombination of data types, the general purpose media processor 12 isdynamically partitionable to allocate the appropriate amount ofprocessing for each combination of media in a unified media data stream.A block diagram of two preferred general purpose media processor systemconfigurations is shown in FIG. 6. Referring to FIG. 6, a generalpurpose media processor 12 is coupled to a high-speed back plane 90. Thepresently preferred back plane 90 is capable of operation at 30 gigabitsper second. As those skilled in the art will appreciate, back planes 90that are capable of operation at 400 gigabits per second or greaterbandwidth are envisioned within the spirit and scope of the invention.Multiple memory devices 92 are also coupled to the back plane 90, whichare accessible by the general purpose media processor 12. Input/outputdevices 94 are coupled to the back plane 90 through a dual-ported memory92. The configuration of the input/output devices 94 on one end of thedual-ported memory 92 allows the sharing of these memory devices 92throughout a network 38 of general purpose media processors 12.

Alternatively, FIG. 6 shows a presently preferred integrated generalpurpose media processor 12. The integrated processor includes on-boardmemory and I/O 86. The on-board memory is preferably of sufficient sizeto optimize throughput, and can comprise a cache and/or buffer memory orthe like. The integrated media processor 12 also connects to externalmemory 88, which is preferably larger than the on-board memory 86 andforms the system main memory.

Execution Unit

One presently preferred embodiment of an integrated general purposemedia processor 12 is shown in FIG. 7. The core of the integratedgeneral purpose media processor 12 comprises an execution unit 100.Three main elements or subsections are included in the execution unit100. A multiple precision arithmetic/logic unit ("ALU") 102 performs alllogical and simple arithmetic operations on incoming media data streams.Such operations consist of calculate and control operations such asBoolean functions, as well as addition, subtraction, multiplication anddivision. These operations are performed on single or unified media datastreams transmitted to and from the multiple precision ALU 102 over adata bus or data path 108. Preferably the data path 108 is 128 bitswide, although those skilled in the art will appreciate that the datapath 108 can take on any width or size without departing from the spiritand scope of the invention. The wider the data path 108 the more unifiedmedia data can be processed in parallel by the general purpose mediaprocessor 12.

Coupled to the multi-precision ALU 102 via the data path 108, and alsoan element of the execution unit 100, is a programmable switch 104. Theprogrammable switch 104 performs data handling operations on single orunified media data streams transmitted over the data path 108. Examplesof such data handling operations include deals, shuffles, shifts,expands, compresses, swizzles, permutes and reverses, although otherdata handling operations are contemplated. These operations can beperformed on single bits or bit fields consisting of two or more bits upto the entire width of the data path 108. Thus, single bits or bitfields of various sizes can be manipulated through programmableoperation of the switch 104.

Examples of the presently preferred data manipulation operationsperformed by the general purpose media processor 12 are shown in FIG. 8.A group expand operation is visually illustrated in FIG. 8(a). Accordingto the group expand operation, a sequential field of bits 270 can bedivided into constituent sub-fields 272a-272d for insertion into alarger field array 274. The reverse of the group expand operation is agroup compress or extract operation. A visual illustration of the groupcompress or extract operation is shown in FIG. 8(b). As shown, separatesub-fields 272a-272d from a larger bit field 274 can be combined to forma contiguous or sequential field of bits 270.

Referring to FIGS. 8(c)-8(e), group deal, shuffle, swizzle and permuteoperations performed by the programmable switch 104 are alsoillustrated. The operations performed by these instructions are readilyunderstood from a review of the drawings. The group manipulationoperations illustrated in FIGS. 8(a)-8(e) comprise the presentlycontemplated data manipulation operations for the general purpose mediaprocessor 12. As those skilled in the art will appreciate, either asubset of these operations or additional data manipulation operationscan be incorporated in other alternate embodiments of the generalpurpose media processor 12 without departing from the spirit and scopeof the invention.

Referring again to FIG. 7, higher level mathematical operations thanthose performed by the multi-precision ALU 102 are performed in thegeneral purpose media processor 12 through an extended math element 106.The extended math element 106 is coupled to the data path 108 and alsocomprises part of the execution unit 100. The extended math element 106performs the complex arithmetic operations necessary for video datacompression and similarly intensive mathematical operations. Onepresently preferred example of an extended math operation comprises aGalois field operation. Other examples of extended mathematicalfunctions performed by the extended math element 106 include CRCgeneration and checking, Reed-Solomon code generation and checking, andspread-spectrum encoding and decoding. As those skilled in the artappreciate, additional mathematical operations are possible andcontemplated.

According to the preferred embodiment of the integrated general purposemedia processor 12, a register file 110 is provided in addition to theexecution unit 100 to process media data. The register file 110 storesand transmits data streams to and from the execution unit 100 via thedata path 108. Rather than employing a complex set of specific ordedicated registers, the general purpose media processor 12 preferablyincludes 64 general purpose registers in the register file 110 alongwith one program counter (not shown). The 64 general purpose registerscontained in the register file 110 are all available to theuser/programmer, and comprise a portion of the user state of the generalpurpose media processor 12. The general purpose registers are preferablycapable of storing any form of data. Each register within the registerfile 110 is coupled to the data path 108 and is accessible to theexecution unit 100 in the same manner. Thus, the user can employ ageneral purpose register according to the specific needs of a particularprogram or unique application. As those skilled in the art willappreciate, the register file 110 can also comprise a plurality ofregister files 110 configured in parallel in order to support parallelmulti-threaded processing.

Instruction Set and User Programming

Control or manipulation of data processed by the general purpose mediaprocessor 12 is achieved by selected instructions programmed by theuser. Those skilled in the art will appreciate that a great number ofprograms are possible through various sequences of instructions.Particular programs can be developed for each unique implementation ofthe general purpose media processor 12. A detailed discussion of suchspecific programs is therefore beyond the scope of this description.

One presently preferred instruction set for the general purpose mediaprocessor 12 is included in the Microfiche Appendix, the contents ofwhich are hereby incorporated herein by reference. A list of thepresently preferred major operation codes for the general purpose mediaprocessor 12 appears below in Table I.

    __________________________________________________________________________    MAJOR OPERATION CODES                                                         MAJOR                                                                             0       32       64      96       128  160    192   224                   __________________________________________________________________________    0   ERES    GSHUFFLEI                                                                              FMULADD16                                                                             GMULADD1 LU16LAI                                                                            SAAS64LAI                                                                            EADDIO                                                                              BFE16                 1   ESHUFFLE-                                                                             GSHUFFLE-                                                                              FMULADD32                                                                             GMULADD2 LU16BAI                                                                            SAAS64BAI                                                                            EADDIUO                                                                             BFNUE16                   I4MUX   I4MUX                                                             2           GSELECT8 FMULADD64                                                                             GMULADD4 LU16LI                                                                             SCAS64LAI                                                                            ESETIL                                                                              BFNUGE16              3   EMDEPI  GMDEPI           GMULADD8 LU16BI                                                                             SCAS64BAI                                                                            ESETIGE                                                                             BFNUL16               4   EMUX    GMUX     FMULSUB16                                                                             GMULADD16                                                                              LU32LAI                                                                            SMAS64LAI                                                                            ESETIE                                                                              BFE32                 5   E8MUX   G8MUX    FMULSUB32                                                                             GMULADD32                                                                              LU32BAI                                                                            SMAS64BAI                                                                            ESETINE                                                                             BFNUE32               6   EGFMUL64                                                                              GGFMUL8  FMULSUB64                                                                             GMULADD64                                                                              LU32LI                                                                             SMUX64LAI                                                                            ESETIUL                                                                             BFNUGE32              7   ETRANSPOSE-                                                                           GTRANSPOSE-      GEXTRACT128                                                                            LU32BI                                                                             SMUX64BAI                                                                            ESETIUGE                                                                            BFNUL32                   aMUX    8MUX                                                              8                                     L16LAI                                                                             S16LA1 ESUBIO                                                                              BFE64                 9   ESWIZZLE                                                                              GSWIZZLE         GUMULADD2                                                                              L16BAI                                                                             S16BAI ESUBIUO                                                                             BFNUE64               10          GSWIZZLECOPY     GUMULADD4                                                                              L16LI                                                                              S16LI  ESUBIL                                                                              BFNUGE64              11          GSWIZZLESWAP     GUMULADD8                                                                              L16BI                                                                              S16B1  ESUBIGE                                                                             BFNUL64               12  EDEPI   GDEPI    F.16    GUMULADD16                                                                             L32LAI                                                                             S32LAI ESUBIE                                                                              BFE128                13  EUDEPI  GUDEPI   F.32    GUMULADD32                                                                             L32BAI                                                                             S32BAI ESUBINE                                                                             BFNUE128              14  EWTHI   GWTHI    F.64    GUMULADD64                                                                             L32LI                                                                              S32LI  ESUBIUL                                                                             BFNUGE128             15  EUWTHI  GUWTHI           GUEXTRACT128                                                                           L32BI                                                                              S32BI  ESUBIUGE                                                                            BFNUL128              16                   GFMULADD16                                                                            GEXTRACTI                                                                              L64LAI                                                                             S64LAI EADDI BANDE                 17                   GFMULADD32                                                                            GEXTRACTI16                                                                            L64BAI                                                                             S64BAI EXORI BANDNE                18                   GFMULADD64                                                                            GEXTRACT132                                                                            L64LI                                                                              S64LI  EORI  BL/BLZ                19                   GFMULADD128                                                                           GUEXTRACTI64                                                                           L64BI                                                                              S64BI  EANDI BGE/BGEZ              20                   GFMULSUB16                                                                            GEXTRACT L128LAI                                                                            S128LAI                                                                              ESUBI BE                    21                   GFMULSUB32                                                                            .I.64    L128BAI                                                                            S128BAI      BNE                   22                   GFMULSUB64                                                                            G.EXTRACT                                                                              L128LI                                                                             S128LI ENORI BUL/BGZ               23                   GFMULSUB128                                                                           .I.128   L128BI                                                                             S128BI ENANDI                                                                              BUGE/BLEZ             24                           G.1      LBI  SBI          BGATEI                25                           G.2      LUBI                                    26                           G.4                                              27                           G.8                                              28          ECOPYI   GF.16   G.16                 ECOPYI                                                                              BI                    29                   GF.32   G.32                       BLINKI                30                   GF.64   G.64                                             31          E.MINOR  GF.128  G.128    L.MINOR                                                                            S.MINOR                                                                              E.MINOR                                                                             B.MINOR               major operation code field values                                             __________________________________________________________________________

As shown in Table I, the major operation codes are grouped according tothe function performed by the operations. The operations are thusarranged and listed above according to the presently preferred operationcode number for each instruction. As many as 255 separate operations arecontemplated for the preferred embodiment of the general purpose mediaprocessor 12. As shown in Table I, however, not all of the operationcodes are presently implemented. As those skilled in the art willappreciate, alternate schemes for organizing the operation codes, aswell as additional operation codes for the general purpose mediaprocessor 12, are possible.

The instructions provided in the instruction set for the general purposemedia processor 12 control the transfer, processing and manipulation ofdata streams between the register file 110 and the execution unit 100.The presently preferred width of the instruction path 112 is 32-bitswide, organized as four eight-bit bytes ("quadlets"). Those skilled inthe art will appreciate, however, that the instruction path 112 can takeon any width without departing from the spirit and scope of theinvention. Preferably, each instruction within the instruction set isstored or organized in memory on four-byte boundaries. The presentlypreferred format for instructions is shown in FIG. 9(a).

As shown in FIG. 9(a), each of the presently preferred instructionformats for the general purpose media processor 12 includes a field 280for the major operation code number shown in Table I. Based on the typeof operation performed, the remaining bits can provide additionaloperands according to the type of addressing employed with theoperation. For example, the remainder of the 32-bit instruction fieldcan comprise an immediate operand ("imm"), or operands stored in any ofthe general registers ("ra," "rb," "rc," and "rd"). In addition, minoroperation codes 282 can also be included among the operands of certain32-bit instruction formats.

The presently preferred embodiment of the general purpose mediaprocessor 12 includes a limited instruction set similar to those seen inReduced Instruction Set Computer ("RISC") systems. The preferredinstruction set for the general purpose media processor 12 shown inTable I includes operations which implement load, store, synchronize,branch and gateway functions. These five groups of operations can bevisually represented as two general classes of related operations. Thebranch and gateway operations perform related functions on media datastreams and are thus visually represented as block 114 in FIG. 7.Similarly, the load, store and synchronize operations are groupedtogether in block 116 and perform similar operations on the media datastreams. (Blocks 114 and 116 only represent the above classification ofthese operations and their function in the processing of media datastreams, and do not indicate any specific underlying electronicconnections.) A more detailed discussion of these operations, and thefunctionality of the general purpose media processor 12, appears in theMicrofiche Appendix.

The four-byte structure of instructions for the general purpose mediaprocessor 12 is preferably independent of the byte ordering used for anydata structures. Nevertheless, the gateway instructions are specificallydefined as 16-byte structures containing a code address used to securelyinvoke a procedure at a higher privilege level. Gateways are preferablymarked by protection information specified in the translation lookasidebuffer 148 in the memory management unit 122. Gateways are thuspreferably aligned on 16-byte boundaries in the external memory. Inaddition to the general purpose registers and program counter, aprivilege level register is provided within the register file 110 thatcontains the privilege level of the currently executing instruction.

The instruction set preferably includes load and store instructions thatmove data between memory and the register file 110, branch instructionsto compare the content of registers and transfer control, and arithmeticoperations to perform computations on the contents of registers. Swapinstructions provide multi-thread and multi-processor synchronization.These operations are preferably indivisible and include suchinstructions as add-and-swap, compare-and-swap, and multiplex-and-swapinstructions. The fixed-point compare-and-branch instructions within theinstruction set shown in Table I provide the necessary arithmetic testsfor equality and inequality of signed and unsigned fixed-point values.The branch through gateway instruction provides a secure means to accesscode at a higher privileged level in a form similar to a high levellanguage procedure call generally known in the art.

The general purpose media processor 12 also preferably supportsfloating-point compare-and-branch instructions. The arithmeticoperations, which are supported in hardware, include floating-pointaddition, subtraction, multiplication, division and square root. Thegeneral purpose media processor 12 preferably supports otherfloating-point operations defined by the ANSI-IEEE floating-pointstandard through the use of software libraries. A floating point valuecan preferably be 16, 32, 64 or 128-bits wide. Examples of thepresenting preferred floating-point data sizes are illustrated in FIG.9(b).

The general purpose media processor 12 preferably supports virtualmemory addressing and virtual machine operation through a memorymanagement unit 122. Referring to FIG. 10(a), one presently preferredembodiment of the memory management unit 122 is shown. The memorymanagement unit 122 preferably translates global virtual addresses intophysical addresses by software programmable routines augmented by ahardware translation lookaside buffer ("TLB") 148. A facility for localvirtual address translation 164 is also preferably provided. As thoseskilled in the art will appreciate, the memory management unit 122includes a data cache 166 and a tag cache 168 that store data and tagsassociated with memory sections for each entry in the TLB 148.

A block diagram of one preferred embodiment of the TLB 148 is shown inFIG. 10(b). The TLB 148 receives a virtual address 230 as its input. Foreach entry in the TLB 148, the virtual address 230 is logically AND-edwith a mask 232. The output of each respective AND gate 234 is comparedvia a comparator 236 with each entry in the TLB 148. If a match isdetected, an output from the comparator 236 is used to gate data 240through a transceiver 238. As those skilled in the art will appreciate,a match indicates the entry of the corresponding physical address withinthe contents of the TLB 148 and no external memory or I/O access isrequired. The data 240 for the data cache 166 (FIG. 10(a)) is thencombined with the remaining lower bits of the virtual address 230through an exclusive-OR gate 242. The resultant combination is thephysical address 244 output from the TLB 148. If a match is not detectedbetween the logical address and the contents of the tag cache 168, thememory management unit 122 an external memory or I/O access is necessaryto retrieve the relevant portion of memory and update the contents ofthe TLB 148 accordingly.

Using generally known memory management techniques, the memorymanagement unit 122 ensures that instructions (and data) are properlyretrieved from external memory (or other sources) over an externalinput/output bus 126 (see FIG. 7). As described in more detail below, ahigh bandwidth interface 124 is coupled to the external input/output bus126 to communicate instructions (and media data streams) to the generalpurpose media processor 12. The presently preferred physical addresswidth for the general purpose media processor 12 is eight bytes(64-bits). In addition, the memory management unit 122 preferablyprovides match bits (not shown) that allow large memory regions to beassigned a single TLB entry allowing for fine grain memory management oflarge memory sections. The memory management unit 122 also preferablyincludes a priority bit (not shown) that allows for preferential queuingof memory areas according to respective levels of priority. Other memorymanagement operations generally known in the art are also performed bythe memory management unit 122.

Referring again to FIG. 7, instructions received by the general purposemedia processor 12 are stored in a combined instruction buffer/cache118. The instruction buffer/cache 118 is dynamically subdivided to storethe largest sequence of instructions capable of execution by theexecution unit 100 without the necessity of accessing external memory.In a preferred embodiment of the invention, instruction buffer space isallocated to the smallest and most frequently executed blocks of mediainstructions. The instruction buffer thus helps maintain the highbandwidth capacity of the general purpose media processor 12 bysustaining the number of instructions executed per second at or nearpeak operation. That portion of the instruction buffer/cache 118 notused as a buffer is, therefore, available to be used as cache memory.The instruction buffer/cache 118 is coupled to the instruction path 112and is preferably 32 kilobytes in size.

A data buffer/cache 120 is also provided to store data transmitted andreceived to and from the execution unit 100 and register file 110. Thedata buffer/cache 120 is also dynamically subdivided in a manner similarto that of the instruction buffer/cache 118. The buffer portion of thedata buffer/cache 120 is optimized to store a set size of unified mediadata capable of execution without the necessity of accessing externalmemory. In a preferred embodiment of the invention, data buffer space isallocated to the smallest and most frequently accessed working sets ofmedia data. Like the instruction buffer, the data buffer thus maintainspeak bandwidth of the general purpose media processor 12. The databuffer/cache 120 is coupled to the data path 108 and is preferably also32 kilobytes in size.

The preferred embodiment of the general purpose media processor 12includes a pipelined instruction pre-fetch structure. Although pipelinedoperation is supported, the general purpose media processor 12 alsoallows for non-pipelined operations to execute without any operationalpenalty. One preferred pipeline structure for the general purpose mediaprocessor 12 comprises a "super-string" pipeline shown in FIG. 11. Asuper-string pipeline is designed to fetch and execute severalinstructions in each clock cycle. The instructions available for thegeneral purpose media processor 12 can be broken down into five basicsteps of operation. These steps include a register-to-register addresscalculation, a memory load, a register-to-register data calculation, amemory store and a branch operation. According to the super-stringpipeline organization of the general purpose media processor 12, oneinstruction from each of these five types may be issued in each clockcycle. The presently preferred ordering of these operations are aslisted above where each of the five steps are assigned letters "A," "L,""E," "S" and "B" (see FIG. 11).

According to the super-string pipelining technique, each of theinstructions are serially dependent, as shown in FIG. 11, and thegeneral purpose media processor 12 has the ability to issue a string ofdependent instructions in a single clock cycle. These instructions shownin FIG. 11 can take from two to five cycles of latency to execute, and abranch prediction mechanism is preferably used to keep up the pipelinefilled (described below). Instructions can be encoded in unit categoriessuch as address, load, store/sync, fixed, float and branch to allow foreasy decoding. A similar scheme is employed to pre-fetch data for thegeneral purpose media processor 12.

As those skilled in the art will appreciate, the super-string pipelinecan be implemented in a multi-threaded environment. In such animplementation, the number of threads is preferably relatively primewith respect to functional unit rates so that functional units can bescheduled in a non-interfering fashion between each thread.

In another more preferred embodiment, a "super-spring" pipelining schemeis employed with the general purpose media processor 12. Thesuper-spring pipeline technique breaks the super-string pipeline shownin FIG. 11 into two sections that are coupled via a memory buffer (notshown). A visual representation of the super-spring pipeline techniqueis shown in FIG. 12. The front of the pipeline 204, in which addresscalculation (A), memory load (L), and branch (B) operations are handled,is decoupled from the back of the pipeline 206, in which datacalculation (E) and memory store (S) operations are handled. Thedecoupling is accomplished through the memory buffer (not shown), whichis preferably organized in a first-in-first-out ("FIFO") fast/densestructure. (The memory buffer is functionally represented as a spring inFIG. 12.)

As indicated in Table I above, the general purpose media processor 12does not include delayed branch instructions, and so relies upon branchor fetch prediction techniques to keep the pipeline full in programflows around unconditional and conditional branch instructions. Manysuch techniques are generally known in the art. Examples of somepresently preferred techniques include the use of group compare and set,and multiplex operations to eliminate unpredictable branches; the use ofshort forward branches, which cause pipeline neutralization; and wherebranch and link predicts the return address in a one or more entrystack. In addition, the specialized gateway instructions included in thegeneral purpose media processor 12 allow for branches to and fromprotected virtual memory space. The gateway instructions, therefore,allow an efficient means to transfer between various levels ofprivilege.

As described above, two basic forms of media data are processed by thegeneral purpose media processor 12, as shown in FIG. 7. These datastreams generally comprise Nyquist sampled I/O 128, and standard memoryand I/O 130. As shown in FIG. 7, audio 132, video 134, radio 136,network 138, tape 140 and disc 142 data streams comprise some examplesof digitally sampled I/O 128. As those skilled in the art willappreciate, other forms of digitally sampled I/O are contemplated forprocessing by the general purpose media processor 12 without departingfrom the spirit and scope of the invention. Standard memory and I/O 130comprises data received and transmitted to and from general digitalperipheral devices used in the design of most computer systems. As shownin FIG. 7, some examples of such devices include dynamic random accessmemory ("DRAM") 146, or any data received over the PCI bus 144 generallyknown in the art. Other forms of standard memory and I/O sources arealso contemplated. The various fixed-point data sizes preferred for thegeneral purpose media processor 12 are illustrated in FIG. 9(c).

External Interface

As mentioned above, the general purpose media processor 12 includes ahigh bandwidth interface 124 to communicate with external memory andinput/output sources. As part of the high bandwidth interface 124, thegeneral purpose media processor 12 integrates several fast communicationchannels 156 (FIG. 13) to communicate externally. These fastcommunication channels 156 preferably couple to external caches 150,which serve as a buffer to memory interfaces 152 coupled to standardmemory 154. The caches 150 preferably comprise synchronous static randomaccess memory ("SRAM"), each of which are sixty-four kilobytes in size;and the standard memories 154 comprise DRAM's. The memory interfaces 152transmit data between the caches 150 and the standard memories 154. Thestandard memories 154 together form the main external memory for thegeneral purpose media processor 12. The cache 150, memory interface 152,standard memory 154 and input/output channel 156 therefore make up asingle external memory unit 158 for the general purpose media processor12.

According to the presently preferred embodiment of the invention, thememory interface protocol embeds read and write operations to a singlememory space into packets containing command, address, data andacknowledgment information. The packets preferably include check codesthat will detect single-bit transmission errors and some multiple-biterrors. As many as eight operations may be in progress at a time in eachexternal memory unit 158. As shown in FIG. 13, up to four externalmemory units 158 may be cascaded together to expand the memory availableto the general purpose media processor 12, and to improve the bandwidthof the external memory. Through such cascaded memory units 158, thememory interface 152 provides for the direct connection of multiplebanks of standard memory 154 to maintain operation of the generalpurpose media processor 12 at sustained peak bandwidths.

According to one embodiment shown in FIG. 13, up to four standard memorydevices 154 can be coupled to each memory interface 152. Each standardmemory 154 thus includes as many as four banks of DRAM, each of which ispreferably sixteen bits wide. The standard memories 154 are connected inparallel to the memory interface 152 forming a 72-bit wide data bus 160,where 64 bits are preferably provided for data transfer and eight bitsare provided for error correction. In addition to the data bus 160, anaddress/control bus 162 is coupled between the memory interface 152 andeach standard memory 154. The address/control bus 162 preferablycomprises at least twelve address lines (4 kilobits×16 memory size) andfour control lines as shown in FIG. 13. An alternate manner for couplingthe DRAM's to the memory interface 152 is illustrated in FIG. 14. Asshown in FIG. 14, two banks of four DRAM single in-line memory modulesare coupled in parallel to the memory interface 152. The memoryinterface 152 also supports interleaving to enhance bandwidth, and pagemode accesses to improve latency for localized addressing.

Using standard DRAM components, the external memory units 158 achievebandwidths of approximately two gigabits/second with the standardmemories 154. When four such external memory units 158 are coupled viathe communication channel 156, therefore, the total bandwidth of theexternal main memory system increases to one gigabyte/second. Asdiscussed further below, in implementations with two or eightcommunication channels 156, the aggregate bandwidth increases to two andeight gigabytes/second, respectively.

A more detailed depiction of the communication channel 156 circuitryappears in FIG. 15. According to the preferred embodiment of theinvention, each communication channel 156 comprises two unidirectional,byte-wide, differential, packet-oriented data channels 156a, 156b (seeFIG. 13). As explained above, where memory units 158 are cascadedtogether in series, the output of one memory unit 158 is connected tothe input of another memory unit 158. The two unidirectional channelsare thus connected through the memory units 158 forming a loop structureand make up a single bi-directional memory interface channel.

Referring to FIG. 15, each communication channel 156 is preferably eightbits wide, and each bit is transmitted differentially. For example,output transceiver 170 for bit D_(0out) transmits both D₀ and /D₀signals over the communication channel 156. Additional transceivers aresimilarly provided for the remaining bits in the channel 156. (Thetransceiver 176 for bit D_(7out) and associated differential lines 178,180 are shown in FIG. 15.) A CLK_(out) transceiver 182 is also providedto generate differential clock outputs 184, 186 over the channel 156. Tocomplete the link between memory units 158, input transceivers 188-192are provided in each memory unit 158 for each of the differential bitsand clock signals transmitted over the communication channel 156. Theseinput signals 172, 174, 178, 180, 184, 186 are preferably transmittedthrough input buffers 194-198 to other parts of the memory unit 158(described above).

Each memory unit 158 also includes a skew calibrator 200 and phaselocked loop ("PLL") 202. The skew calibrator 200 is used to control skewin signals output to the communication channel 156. Preferably, digitalskew fields are employed, which include set numbers of delay stages tobe inserted in the output path of the communication channel 156. Settingthese fields, and the corresponding analog skew fields, permits a finelevel of control over the relative skew between output channel signals.

The PLL 202 recovers the clock signal on either side of thecommunication channel 156 and is thus provided to remove clock jitter.The clock signals 184, 186 preferably comprise a single phase, constantrate clock signal. The clock signals 184, 186 thus contain alternatingzero and one values transmitted with the same timing as the data signals172, 174, 178, 180. The clock signal frequency is, therefore, one-halfthe byte data rate. The communication channel 156 preferably operates atconstant frequency and contains no auxiliary control, handshaking orflow control information.

Each external memory unit 158 preferably defines two functional regions:a memory region, implemented by the cache 150 backed by standard memory154 (see FIG. 13), and a configuration region, implemented by registers(not shown). Both regions are accessed by separate interfaces; thecommunication channel 156 is used to access the memory region, and aserial interface (described below) is used to access the configurationregion. In the memory region, the caches 150 are preferably write-back(write-in) single-set (direct-map) caches for data originally containedin standard memory 154. All accesses to memory space should maintainconsistency between the contents of the cache 150 and the contents ofthe standard memory 154. The configuration region registers provide themechanism to detect and adjust skew in the communication channel 156.Software is preferably employed to adaptively adjust the skew in thechannel 156 through digital skew fields, as explained above. The serialinterface thus is used to configure the external memory units 158, setdiagnostic modes and read diagnostic information, and to enable the useof a high-speed tester (not shown).

One presently preferred embodiment of the invention employs twobyte-wide packet communication channels 156 (FIG. 16(a)). In order tofurther increase the bandwidth of the general purpose media processor12, up to sixteen byte-wide packet communication channels 156 can beemployed. Referring to FIG. 16(b), twelve communication channels,comprising eight memory channels 210, a ninth channel for parallelprocessing 212 (described below), and three input/output ("I/O")channels 214, are shown. Each of the communication channels 210-214preferably employs the cascade configuration of four channel interfacedevices 216. (Each channel interface device 216 coupled to the memorychannels 210 corresponds to the external memory unit 158 shown in FIG.13.) Through each of the twelve communication channels shown in FIG.16(b), the general purpose media processor 12 can request or issue reador write transactions. When not interleaved, the twelve channels providea single contiguous memory space for each channel interface device 216.

Alternatively, memory accesses may be interleaved in order to providefor continuous access to the external memory system at the maximumbandwidth for the DRAM memories. In an interleaved configuration, at anypoint in time some memory devices will be engaged in row pre-charge,while others may be driving or receiving data, or receiving row orcolumn addresses. The memory interface 152 (FIG. 13) thus preferablymaps between a contiguous address space and each of the separate addressspaces made available within each external memory unit 158. For maximumperformance, therefore, the memory interface is interleaved so thatreferences to adjacent addresses are handled by different memorydevices. Moreover, in the preferred embodiment, additional memoryoperations may be requested before the corresponding DRAM bank isavailable. In an interleaved approach, these operations are placed in aqueue until they can be processed. According to the preferredembodiment, memory writes have lower priority than memory reads, unlessan attempt is made to read an address that is queued for a writeoperation. As those skilled in the art will appreciate, the depth of thememory write queue is dictated by the specific implementation.

Although up to four external memory units 158 are preferably cascaded toform effectively larger memories, some amount of latency may beintroduced by the cascade. Packets of data transmitted over thecommunication channel 156 are uniquely addressed to a particular channelinterface device 216. A packet received at a particular device, whichspecifies another module address, is automatically passed to the correctchannel interface device 216. Unless the module address matches aparticular device 216, that packet simply passes from the input to theoutput of the interface device 216. This mechanism divides the serialinterconnection of interface devices 216 into strings, which function asa single larger memory or peripheral, but with possibly longer responselatency.

In addition to the memory channels 210, the general purpose mediaprocessor 12 provides several communication channels 214 forcommunication with external input/output devices. Referring to FIG.16(b), three input/output channels 214 having SRAM buffered memory (seeFIG. 13) provide an interface to external standard I/O devices (notshown). Like the eight memory channels 210, the three I/O channels 214are byte-wide input/output channels intended to operate at rates of atleast one gigahertz. The three I/O channels 214 also operate as a packetcommunication link to synchronous SRAM memory 208 within the channelinterface device 216. A controller 226 within the channel interfacedevice 216 completes the interface to the I/O devices.

The three I/O channels 214 preferably function in like manner to thememory channels 210 described above. The interface protocol for thethree I/O channels 214 divides read and write operations to a singlememory space into packets containing command, address, data andacknowledgment information. The packets also include a check code thatwill detect single-bit transmission errors and some multiple-bit errors.According to the preferred embodiment of the invention, as many as eightoperations may progress in each interface device 216 at a time. As shownin FIG. 16(b), up to four channel interface devices 216 can be cascadedtogether to expand the bandwidth in the three I/O channels 214. Abit-serial interface (not shown) is also provided to each of the channelinterface devices 216 to allow access to configuration, diagnostic andtester information at standard TTL signal levels at a more moderate datarate. (A more detailed description of the serial interface is providedbelow).

Like the memory channels 210, each I/O channel 214 includes ninesignals--one clock signal and eight data signals. Differential voltagelevels are preferably employed for each signal. Each channel interfacedevice 216 is preferably terminated in a nominal 50 ohm impedance toground. This impedance applies for both inputs and outputs to thecommunication channel 156. A programmable termination impedance ispreferred.

Interface Communication

According to one presently preferred embodiment of the invention, thechannel interface devices 216 can operate as either master devices orslave devices. A master device is capable of generating a request on thecommunication channel 156 and receiving responses from the communicationchannel 156. Slave devices are capable of receiving requests andgenerating responses, over the communication channel 156. A masterdevice is preferably capable of generating a constant frequency clocksignal and accepting signals at the same clock frequency over thecommunication channel 156. A slave device, therefore, should operate atthe same clock rate as the communication channel 156, and generate nomore than a specified amount of variation in output clock phase relativeto input clock phase. The master device, however, can accept anarbitrary input clock phase and tolerates a specified amount ofvariation in clock phase over operating conditions.

Packets of information sent over the communication channel 156preferably contain control commands, such as read or write operations,along with addresses and associated data. Other commands are provided toindicate error conditions and responses to the above commands. When thecommunication channel 156 is idle, such as during initialization andbetween transmitted packets, an idle packet, consisting of an all-zerobyte and an all-one byte is transmitted through the communicationchannel 156. Each non-idle packet consists of two bytes or a multiple oftwo bytes, and begins with a byte having a value other than all zeros.All packets transmitted over the communication channel 156 also beginduring a clock period in which the clock signal is zero, and all packetspreferably end during a clock period in which the clock signal is one. Adepiction of the preferred packet protocol format for transmission overthe communication channel 156 appears in FIG. 17.

The general form of each packet is an array of bytes preferably withouta specific byte ordering. The first byte contains a module address 250("ma") in the high order two bits; a packet identifier, usually acommand 252 ("com"), in the next three bit positions; and a linkidentification number 254 ("lid") in the last three bit positions. Theinterpretation of the remaining bytes of a packet depend upon thecontents of the packet identifier. The length of each packet ispreferably implied by the command specified in the initial byte of thepacket. A check byte is provided and computed as odd bit-wise paritywith a leftward circular rotation after accumulating each byte. Thistechnique provides detection of all single-bit and some multiple-biterrors, but no correction is provided.

The modular address 250 field of each packet is preferably a two-bitfield and allows for as many as four slave devices to be operated from asingle communication channel 156. Module address values can be assignedin one of two fashions: either dynamically assigned through aconfiguration register (not shown), or assigned via static/geometricconfiguration pins. Dynamic assignment through a configuration registeris the presently preferred method for assigning module address values.

The link identification number 254 field is preferably 3-bits wide andprovides the opportunity for master devices to initiate as many as eightindependent operations at any one time to each slave device. Eachoutstanding operation requires a distinct link identification number,but no ordering of operations should be implied by the value of the linkidentification field. Thus, there is preferably no requirement for linkidentification values 254 to be sequentially assigned either in requestsor responses.

The receipt of packets over the communication channel 156 that do notconform to the channel protocol preferably generates an error condition.As those skilled in the art will appreciate, the level or degrees towhich a specific implementation detects errors is defined by the user.In one presently preferred embodiment of the invention, all errors aredetected, and the following protocol is employed for handling errors.For each error detected, the channel interface device 216 causes aresponse explicitly indicating the error condition. Channel interfacedevices 216 reporting an invalid packet will then suppress the receiptof additional packets until the error is cleared. The transmitted packetis otherwise ignored. However, even though the erroneous packet isignored, the channel interface devices 216 preferably continue toprocess valid packets that have already been received and generateresponses thereto. An identification of the presently preferred commands252 to be used over the communication channel 156 are listed in FIG. 17.

In the master/slave preferred embodiment, the channel interface devices216 forward packets that are intended for other devices connected to thecommunication channel 156, as described above. In slave devices,forwarding is performed based on the module address 250 field of thepacket. Packets which contain a module address 250 other than that ofthe current device are forwarded on to the next device. All non-idlepackets are thus forwarded including error packets. In master devices,forwarding is performed based on the link identifier number 254 of thepacket. Packets that contain link identifier numbers 254 not generatedby the specific channel interface device 216 are forwarded. In order toreduce transmission latency, a packet buffer may be provided. As thoseskilled in the art appreciate, the suitable size for the packet bufferdepends on the amount of latency tolerable in a particularimplementation.

A variety of master/slave ring configurations are possible using thehigh bandwidth interface 124 of the invention. Five ring configurationsare currently preferred: single-master, dual-master, multiple-master,single-slave and multiple-master/multiple-slave. The simplest ringconfiguration contains a single non-forwarding master device and asingle non-forwarding slave device. No forwarding is required for eitherdevice in this configuration as packets are sent directly to therecipient. A single-master ring, however, may contain a cascade of up tofour slave devices (see FIGS. 13, 16). In the single-master ringconfiguration, each slave device is configured to a distinct moduleaddress, and each slave device forwards packets that contain moduleaddress fields unequal to their own. As discussed above, a single-masterring provides a larger memory or I/O capacity than a master-slave pair,but also introduces a potentially longer response latency. In thesingle-master ring, each slave device may have as many as eighttransactions outstanding at any time, as described above.

The remaining combinations share many of the above basic attributes. Ina dual-master pair, each master device may initiate read and writeoperations addressed to the other, and each may have up to eight suchtransactions outstanding. No forwarding is required for either devicebecause packets are sent directly to the recipient. A multiple-masterring may contain multiple master devices and a single slave device. Inthis configuration, the slave device need not forward packets as allinput packets are designated for the single slave device. Amultiple-master ring may contain multiple master devices and as many asfour slave devices. Each slave device may have up to eight transactionsoutstanding, and each master device may use some of those transactions.In a preferred embodiment, a master also has the capability to detect atime-out condition or when a response to a request packet is notreceived. Further aspects of inter-processor communications andconfigurations are discussed below in connection with FIG. 18.

Serial Bus

In one preferred embodiment of the invention, the general purpose mediaprocessor 12 includes a serial bus (not shown). The serial bus isdesigned to provide bootstrap resources, configuration, and diagnosticsupport to the general purpose media processor 12. The serial buspreferably employs two signals, both at TTL levels, for directcommunication among many devices. In the preferred embodiment, the firstsignal is a continuously running clock, and the second signal is anopen-collector bi-directional data signal. Four additional signalsprovide geographic addresses for each device coupled to the serial bus.A gateway protocol, and optional configurable addressing, each provide ameans to extend the serial bus to other buses and devices. Although theserial bus is designed for implementation in a system having a generalpurpose media processor 12, as those skilled in the art will appreciate,the serial bus is applicable to other systems as well.

Because the serial bus is preferably used for the initial bootstrapprogram load of the general purpose media processor 12, the bootstrapROM is coupled to the serial bus. As a result, the serial bus needs tobe operational for the first instruction fetch. The serial bus protocolis therefore devised so that no transactions are required for initialbus configuration or bus address assignment.

According to the preferred embodiment, the clock signal comprises acontinuously running clock signal at a minimum of 20 megahertz. Theamount of skew, if any, in the clock signal between any two serial busdevices should be limited to be less than the skew on the data signal.Preferably, the serial data signal is a non-inverted open collectorbi-directional data signal. TTL levels are preferred for communicationon the serial bus, and several termination networks may be employed forthe serial data signal. A simple preferred termination network employs aresistive pull-up of 220 ohms to 3.3 volts above V_(ss). An alternateembodiment employs a more complex termination network such as atermination network including diodes or the "Forced Perfect Termination"network proposed for the SCSI-2 standard, which may be advantageous forlarger configurations.

The geographic addressing employed in the serial bus is provided toinsure that each device is addressable with a number that is uniqueamong all devices on the bus and which also preferably reflects thephysical location of the device. Thus, the address of each deviceremains the same each time the system is operated. In one preferredembodiment, the geographic address is composed of four bits, thusallowing for up to 16 devices. In order to extend the geographicaddressing to more than 16 devices, additional signals may be employedsuch as a buffered copy of the clock signal or an inverted copy of theclock signal (or both).

The serial bus preferably incorporates both a bit level and packetprotocol. The bit level protocol allows any device to transmit one bitof information on the bus, which is received by all devices on the busat the same time. Each transmitted bit begins at the rising edge of theclock signal and ends at the next rising edge. The transmitted bit valueis sampled at the next rising edge of the clock signal. According to onepreferred embodiment where the serial data signal is an open collectorsignal, the transmission of a zero bit value on the bus is achieved bydriving the serial data signal to a logical low value. In thisembodiment, the transmission of a one bit value is achieved by releasingthe serial data signal to obtain a logical high value. If more than onedevice attempts to transmit a value on the same clock, the resultingvalue is a zero if any device transmits a zero value, and one if alldevices transmit a one value. This provides a "wired-AND" collisionmechanism, as those skilled in the art will appreciate. If two or moredevices transmit the same value on the same clock cycle, however, nodevice can detect the occurrence of a collision. In such cases, thetransaction, which may occur frequently in some implementations,preferably proceeds as described below.

The packet protocol employed with the serial bus uses the bit levelprotocol to transmit information in units of eight bits or multiples ofeight bits. Each packet transmission preferably begins with a start bitin which the serial data signal has a zero (driven) value. Aftertransmitting the eight data bits, a parity bit is transmitted. Thetransmission continues with additional data. A single one (released) bitis transmitted immediately following the least significant bit of eachbyte signaling the end of the byte.

On the cycle following the transmission of the parity bit, any devicemay demand a delay of two cycles to process the data received. The twocycle delay is initiated by driving the serial data signal (to a zerovalue) and releasing the serial data signal on the next cycle. Beforereleasing the serial data signal, however, it is preferable to insurethat the signal is not being driven by any other device. Further delaysare available by repeating this pattern.

In order to avoid collisions, a device is not permitted to start atransmission over the serial bus unless there are no currently executingtransactions. To resolve collisions that may occur if two devices begintransmission on the same cycle, each transmitting device shouldpreferably monitor the bus during the transmission of one (released)bits. If any of the bits of the byte are received as zero whentransmitting a one, the device has lost arbitration and must ceasetransmission of any additional bits of the current byte or transaction.

According to the preferred embodiment of the invention, a serial bustransaction consists of the transmission of a series of packets. Thetransaction begins with a transmission by the transaction initiator,which specifies the target network, device, length, type and payload ofthe transaction request. The transaction terminates with a packet havinga type field in a specified range. As a result, all devices connected tothe serial bus should monitor the serial data signal to determine whentransactions begin and end. A serial bus network may have multiplesimultaneous transactions occurring, however, so long as the target andinitiator network addresses are all disjoint.

Parallel Processing

In one preferred embodiment of the invention, two or more generalpurpose media processors 12 can be linked together to achieve a multipleprocessor system. According to this embodiment, general purpose mediaprocessors 12 are linked together using their high bandwidth interfacechannels 124, either directly or through external switching components(not shown). The dual-master pair configuration described above can thusbe extended for use in multiple-master ring configurations. Preferably,internal daemons provide for the generation of memory references toremote processors, accesses to local physical memory space, and thetransport of remote references to other remote processors. In amulti-processor environment, all general purpose media processors 12 runoff of a common clock frequency, as required by the communicationchannels 156 that connect between processors.

Referring to FIG. 18, each general purpose media processor 12 preferablyincludes at least a pair of inter-processor links 218 (see also FIG.16(b)). In one configuration, both pairs of inter-processor links 218can be connected between the two processors 12 to further enhancebandwidth. As shown in FIG. 18(a) several processors 12 may beinterconnected in a linear network employing the transponder daemons ineach processor. In an alternate embodiment shown in FIG. 18(b), theinter-processor links 218 may be used to join the general purpose mediaprocessors 12 in a ring configuration. Alternatively still, generalpurpose media processors 12 may be interconnected into a two-dimensionalnetwork of processors of arbitrary size, as shown in FIG. 18(c). Sixteenprocessors are connected in FIG. 18(c) by connecting four ring networks.In yet another alternate embodiment, by connecting the inter-processorlinks 218 to external switching devices (not shown), multi-processorswith a large number of processors can be constructed with an arbitraryinterconnection topology.

The requester, responder and transponder daemons preferably handle allinter-processor operations. When one general purpose media processor 12attempts a load or store to a physical address of a remote processor,the requester daemon autonomously attempts to satisfy the remote memoryreference by communicating with the external device. The external devicemay comprise another processor 12 or a switching device (not shown) thateventually reaches another processor 12. Preferably, two requesterdaemons are provided each processor 12, which act concurrently on twodifferent byte channels and/or module addresses. The responder daemonaccepts writes from a specified channel and module address, whichenables an external device to generate transaction requests in localmemory or to generate processor events. The responder daemon alsogenerates link level writes to the same external device thatcommunicated responses for the received transaction request. Two suchresponder daemons are preferably provided; each of which operateconcurrently to two different byte channels and/or module addresses.

The transponder daemon accepts writes from a specified channel andmodule address, which enable an external device to cause a requesterdaemon to generate a request on another channel and module address.Preferably, two such transponder daemons are provided, each of which actconcurrently (back-to-back) between two different byte channel and/ormodule addresses. As those skilled in the art will appreciate, therequester, responder and transponder daemons must act cooperatively toavoid deadlock that may arise due to an imbalance of requests in thesystem. Deadlocks prevent responses from being routed to theirdestinations, which may defeat the benefits of a multi-processordistributed system.

According to one presently preferred embodiment of the invention, thegeneral purpose media processor 12 can be implemented as one or moreintegrated circuit chips. Referring to FIG. 19, the presently preferredembodiment of the general purpose media processor 12 consists of afour-chip set. In the four-chip set, a general purpose media processor12 is manufactured as a stand alone integrated circuit. The stand aloneintegrated circuit includes a memory management unit 122, instructionand data cache/buffers 118, 120, and an execution unit 100. A pluralityof signal input/output pads 260 are provided around the circumference ofthe integrated circuit to communicate signals to and from the generalpurpose media processor 12 in a manner generally known in the art.

The second and third chips of the four-chip set comprise in an externalmemory element 158 and a channel interface device 216. The externalmemory element 158 includes an interface to the communication channel156, a cache 150 and a memory interface 152. The channel interfacedevice 216 also includes an interface to the communication channel 156,as well as buffer memory 262, and input/output interfaces 264. Both theexternal memory element 158 and the channel interface device 216 includea plurality of input/output signal pads 260 to communicate signals toand from these devices in a generally known manner.

The fourth integrated circuit chip comprises a switch 226, which allowsfor installation of the general purpose media processor 12 in theheterogeneous network 38. In addition to the plurality of input/outputpads 260, the switch 226 includes an interface to the communicationchannel 156. The switch 226 also preferably includes a buffer 262, arouter 266, and a switch interface 268.

As those skilled in the art will appreciate, many implementations forthe general purpose media processor 12 are possible in addition to thefour-chip implementation described above. Rather than an integratedapproach, the general purpose media processor can be implemented in adiscrete manner. Alternatively, the general purpose media processor 12can be implemented in a single integrated circuit, or in animplementation with fewer than four integrated circuit chips. Othercombinations and permutations of these implementations are contemplated.

There has been described a system for processing streams of media dataat substantially peak rates to allow for real time communication over alarge heterogeneous network. The system includes a media processor atits core that is capable of processing such media data streams. Theheterogeneous network consists of, for example, the fiber optic/coaxialcable/twisted wire network in place throughout the U.S. To provide forsuch communication of media data, a media processor according to theinvention is disposed at various locations throughout the heterogeneousnetwork. The media processor would thus function both in a servercapacity and at an end user site within the network. Examples of suchend user sites include televisions, set-top converter boxes, facsimilemachines, wireless and cellular telephones, as well as large and smallbusiness and industrial applications.

To achieve such high rates of data throughput, the media processorincludes an execution unit, high bandwidth interface, memory managementunit, and pipelined instruction and data paths. The high bandwidthinterface includes a mechanism for transmitting media data streams toand from the media processor at rates at or above the gigahertzfrequency range. The media data stream can consist of transmission,presentation and storage type data transmitted alone or in a unifiedmanner. Examples of such data types include audio, video, radio, networkand digital communications. According to the invention, the mediaprocessor is dynamically partitionable to process any combination orpermutation of these data types in any size.

A programmable, general purpose media processor system presentssignificant advantages over current multimedia communications. Ratherthan rigid, costly and inefficient specialized processors, the mediaprocessor provides a general purpose instruction set to easeprogrammability in a single device that is capable of performing all ofthe operations of the specialized processor combination. Providing auniform instruction set for all media related operations eliminates theneed for a programmer to learn several different instruction sets, eachfor a different specialized processor. The complexity of programming thespecialized processors to work together and communicate with one anotheris also greatly reduced. The unified instruction set is also moreefficient. Highly specialized general calculation instructions that aretailored to general or special types of calculations rather thanenhancing communication are eliminated.

Moreover, the media processor system can be easily reprogrammed simplyby transmitting or downloading new software over the network. In thespecialized processor approach, new programming usually requires thedelivery and installation of new hardware. Reprogramming the mediaprocessor can be done electronically, which of course is quicker andless costly than the replacement of hardware.

It is to be understood that a wide range of changes and modifications tothe embodiments described above will be apparent to those skilled in theart and are contemplated. It is therefore intended that the foregoingdetailed description be regarded as illustrative rather than limiting,and that it be understood that it is the following claims, including allequivalents, that are intended to define the spirit and scope of thisinvention.

We claim:
 1. A method for processing unified media data streams,comprising the steps of:receiving a plurality of unified media datastreams transmitted over a data path, including presentation,transmission and storage information; dynamically partitioning theunified media data streams based on an elemental symbol width, saidelemental symbol width being equal to or narrower than the data path;and processing the unified media data streams at substantially peakoperation; and wherein the step of processing the unified media datastreams further comprises the steps of: storing the unified media datastreams in a general register file; performing multi-precisionoperations on the stored unified media data streams based on programmedinstructions, the multi-precision arithmetic operations includingboolean, integer and floating point mathematical operations;manipulating component fields of the unified media data streams based onprogrammed instructions that implement copying, shifting and re-sizingoperations; and performing multi-precision mathematical operations onthe stored unified media data streams based on programmed instructions,the mathematical operations including finite group, finite ring andtable look-up operations.
 2. The method defined in claim 1, furthercomprising the steps of:pre-fetching instructions and data to fillinstruction and data pipelines; performing memory management operationsto retrieve instructions and data from external memory; storinginstructions and data in instruction and data cache/buffers; anddynamically allocating buffer storage in the instruction and datacache/buffers to ensure real-time execution.
 3. The method defined inclaim 1, further comprising the step of providing a set of instructionsto process the unified media data streams, the set of instructionsincluding load, store, synchronization, branch and gateway instructions.4. The method defined in claim 3, further comprising the step ofprogramming a sequence of at least one instruction from the set ofinstructions.